Drafting instrument



O. F. GRAFF Aug. 30, 1949.

DRAFTING INSTRUMENT Filed April 2, 1946 INVENTOR.

Patented Aug. 30, 1949 f oEElcE 2,480,362 DRAFTING INSTRUMENT Oscar F. Graff, Washington, D. C. Application April 2, 1946, serial No. 659,045

3 Claims.

This invention relates to a drafting instrument and may be more specifically defined as a combined square, protractor, triangle, scale and str-aight edge.

The invention relates to a drafting instrument which combines several of the basic instruments used by draftsmen into a readily available, simple, compact and light article of manufacture.

The invention is so constructed Iand arranged that it is adapted for use directly on a drawing tablet or a drawing board in which the edges of the tablet or board serve as a guide to assist in properly positioning the drafting instrument relative thereto.

One of the objects of the present invention is to provide a device as 'described in which the triangle may be adjusted relative to suitable guide members so that the triangle may be positioned at any desirable angle with reference to the guide in order that the many forms of drafting may be performed.

A further object of the invention is to provide means for latching the triangle in any of ahumber of adjusted positions relative to said guide members and in which the latching operation entails the simple operation of grasping the guide members which releases the latch and at the same time permits relative movement between the guide members and the triangle.

An additional object is the provision of a sight opening in one of the guide members which enables the draftsman to visually ascertain the correct setting of the triangle with reference to the guide members and the guide members are so attached to the triangle that one edge thereof may be placed directly against the drawing board or tablet so as to serve as a straight edge throughout the length thereof. To this end the guide members are terminated at a point spaced from the straight edge and the guide members are reduced in thickness so that by a simple tilting operation the straight edge may be placed directly-v against the drawing surf-ace vwithout any interference from the guide members which are relatively thick as compared to the thickness of the triangle.

A further object is to provide an instrument of the character described in which the triangle and by the draftsman and the guide members, which are preferably formed of moulded material, are hollowed out wherever possible to eliminate weight without sacrificing strength.

In devices heretofore known of the present type, it has been found that the relative movement between the triangle and guide members causes scratching and mutilation of the surface of the triangle due to the fact that there are large areas of contact between the triangle and guide members. However, in my device the guide members are spaced from the triangle throughout a large portion of their length so that a minimum contact between the triangles and guide members is provided, thereby eliminating to a large extent the scratching, rubbing or mutilation heretofore known.

Other objects and advantages Will be apparent as the description proceeds, it being understood that the illustrated embodiment depicts the preferred form of the device but that changes in proportions, finish and the like may be resorted to so long as they fall within the spirit of the invention as defined in the appended claims.

Reference is made to the drawings attached hereto and forming part hereof wherein like reference numerals refer to corresponding parts throughout the figures and in which:

Figure` 1 is a perspective view of my invention.

Figure 2 is -a fragmentary plan view showing the guide members and triangle in their normal position of use.

Figure 3 is a broken sectional view taken along the line 3-3 of Figure 2.

Figures 4 and 5 are transverse sectional views taken along the lines 4-4 and 5 5 respectively of Figure 2.

Figures 6 and 7 are transverse sectional views taken along the sectional lines 6 6 and 'l-l respectively of Figure 3.

Figures 8, 9 and 10 are diagrammatic illustrations of the'various manners in Which the triangle is used in connection with a drawing board or the like.

Figure 11 is a fragmentary sectional View of a modified construction of the latch.

Referring now in particular to the drawing, the present invention deals with a drafting instrument composed of a transparent triangle, I0, and a guide member II composed of an upper guide member I2 and a lower guide member I3 pivotally attached to the triangle by the rivet I4 passing through the reduced ends I5 and I6 of the guide members and through the triangle so that the triangle is free to swing about the rivet I4 and between the guide members I2 and I3 so that the triangle may be positioned at various angles relative to the inner straight guiding faces of the guide members I2 and I3.

As here illustrated, the guide members I2 and I3 are formed of moulded material such as ruber, synthetic resin or the like, and in order to reduce the weight thereof they are hallowed out as at II and I8.

It should be noted that the guide members I2 and I3, which are reduced at the ends I5 and I6, have the ends of these reduced portions spaced The upper guide member I2 is also provided with a recess 3U which opens outwardly of the end 3 I.

The end 3| and the corresponding end of the lower guide member I3 are secured together by a rivet 32 passing through the said ends and also through an elongated opening 33 in a latch 34 pivoted to the upper member as at 35.

The latch 34.15, provided with a tapered stud 36 and is normally biased toward the triangle Il] by means of a spring 31 so that upon registry with Y :one of the openings 21 the stud will be projected inwardly from the straight edge I9 of the trian- Y gle so that the guide members and tri-angle, as a unit, may be removed from the usual workingposition whereby a guide member is in contact with the side edge of the drawing board', and placedl directly over the drawing, then tilted to bring, the straight edge I9 atly into contact with the drawing surface throughout its length when occasion demands, whereas, if the guide members I2-and -I3'were extended to the edge I9, such edge would be spaced from the drawing surface and could not be brought directly into contact therewith at this point. the rtriangle where it is desired to lay the edge I9 atlyon the drawing surface.

v'The guide members i'Z-and I3 are provided-with aligned spacing `lugs 29- and 2-I, respectively, which projectA beyond the planes of the opposed faces oi the guide members and contact the face of the 4triangle IB.

'The reducedend `por-tions I5 and- IG likewise are held in engagement with the face of the triangle byv means of the rivet |14 but at all other portions the triangle is free from contact with the guide members so that rubbing or scratching of] the triangle in its movement relativeto the guide `members is limited to a restrictedarea and the-adjustment is thereby rendered-less -difcult The triangle I0` is provided with an arcuate slot 22 whichreceives the stud 23, here shown as integrally formed with thev'lower guide .member I3, but .ofcourse this stud'v could be positioned on .either guide `member without Vaffecting -the results.

'Ilhe stud: 231, .pro-jects into Athe arcuate sloti 212 and limits the movement. of. thetriangle-relative totheguide.member.` `By .means of .thistslot the triangle. may quickly .beset ltoaAS? :angleand returnedrto yits voriginal'QOL7 .angle position'.

As shown clearly in Fig. 1, the triangle=is;pro vridedaalongv two ofsitswedgesswith suitable scales 24 and 2'5, it being noted fthatathe scalesread from rightftolleft,asiindicatedinlig. l.

The triangle is also .providedwith .amarcuatel scale 26 and below the scale 26 there is provided a series of arcuately arranged apertures .23.

lIheupper guide-.member I2. is providedzwith a sight opening 28 extending: therethrough and; presenting. an inclined face 29 upon which is placed an, index line Vto facilitate visualdeterminationof y.the Vproperadjust-ment of thetriangle relative to the guide members.

The width ofA thescale 2,6. is substantially vthe width of the sighteopening 2.8and the; scale-2,6 in; its arcuate Yarrangement passes beneath *l `the sightopening 2-81as the. triangle is moved; Therefore the Yindividual,markings -of `the -scale .mayfbe arcuatelyv aligned with :the index` line ron the in-.l clinedface 29 so that proper positioning of thel triangle maybereadily ascertained. 0b.viously, the lower guide membery maylikewise Vbepro-V vided-with a sight openingvsimilar-to thatfjustA described.

This would result in flexing into the same and latch the triangle I0 to its addusted position.

Byreference to Fig. 3 it will be seen that the lower guide member I3 is provided with a countersink 33 intoy `which the triangle I0 fits so that the triangle lies flush with the upper surface of the guide member I3,. although not actually touching the guide member due to the spacing lug 2l. 'The stud 3G of the latch projects `below the-funderface of the upper guide member I2 and rides over the upper face of' the triangle until it registers with an aperture 21 whereupon it is projected into the same by the spring 37.

The upper guide member I2 has its end 'Eil' terminating shortof Vthe end 39 of the lower guide member I3 andthe nnger piece of the latch 3# which projectsbeyond the end 31| of the upper member is positioned: above the reduced end 39 so that the finger piece ofthe latch 3A andthe reduoedend 39 formrgripping surfaces by means of which the operator may readily grasp the same for the purpose of depressing the outer'end ot the latch 3E to thereby. release the'stud 36 fromits aperture after which the .guidermembers and ltriangle may` beswung Arelative toleach other without the necessity of .releasing the grip on the latch. 34 and. end 39; Ater the `correct position betweenthe guide membersianditriangle has rbeen assumed, release of the latch 313: will. cause it to holdrthe'triangle-and guide members in adjusted position.

Itis readily apparent. that it is not essential thatzfthe Vtriangle be provided with a series ofaperturesv as at 2.7., and in Eig. 11; IV have shown another fforrnxof l'atcliing mechanism for accomplishing.r the'fsamepurpose. In this form the tapered stud 36 isreplaced by, an elongated tapered projection I-Uicarniedonfthe undersuriace of the latch and the-triangle is. provided with a series of; -arcuatelyarranged :elongated grooves M- 'to receive fthe-projection fill.`

An examination of-k Figs. 1, 4 and 5 clearlyV shows;-that 1the upper vand lower guide members are irecessedas at vi2 and 4S on theside faces thereof which provide a ready` hand hold by means of, which the instrument may be picked upor manipulated.

It .has ,been Afound initheruse'of triangles of the type-here--disclosed -where the-center `portion vis Openxthatwhenfzthetriangle is usedon a drafting. boardin which the Vdrafting material is held inpositionrby means ofA thumb tacks or the like, that it very oftenliapnens that `theftriangle -must be positioned on the board s0 that one or more of the thumb `wtacks-lie -w-ithin :the open vspace -within the borders fof :the triangle.

In ,suchposition when-an attempt is madero slidefthe 'triangle .alongithe board,` the edges of the triangle surrounding the interior openingengage the tacksforthe'like andthe triangle must be elevated fromthe board in order thatitf-may slideover the iheadsf of the tacks.4

In #order lto :overcome-*the 'necessity- -forelevatev ing the triangle, I provide the edges of the trlangle bordering the interior opening with oppositely beveled surfaces as indicated at 44, so thaty in movement of the triangle along the board the beveled surfaces will ride over the heads of the tacks and eliminate the necessity for elevating the triangle.

While I have described the latch member as being carried by the upper guide member I2, it will be readily apparent that the latch could equally well be carried by the lower member and engage openings in the triangle from beneath or elongated grooves on the bottom face of the triangle.

From the foregoing it is clear that by providing the upper and lower guide members I2 and I3 the inner edges thereof act as guide faces for engagement with an edge of a drawing tablet or board and since the triangle is intermediate the upper and lower guide members, the triangle In view of this possibility it is clear that dey pending upon the position of the drafting instrument isometric or oblique drawings may be made and that with the scales arranged on the triangle as shown and the triangle being transparent, it is clear that when the same is used in its reversed or upside down position the scale on the long leg or hypotenuse may be read correctly.

From the foregoing it is also apparent that the present-l invention embodies a neat, compact and light weight instrument which is adaptable for a variety of forms of drafting. It may be used either in its reversed or normal position. Provision is made for accurately aligning the protractor scale within the sight window and the latch member is substantially completely hidden from View and does not project above the guide members so as to offer an obstacle to the draftsman when using the instrument. Furthermore, it is obvious that the invention is composed of a relatively small number of parts which may be cheaply manufactured, but yet which is of sturdy construction.

The arrangement of the latch 34 projecting beyond the end 3| of the upper guide member cooperating with the reduced grip 39 facilitates disengagement of the latch from the triangle and movement of the guide members relative to the triangle so that the single operation of manipulating the end of the guide memberscarrying the latch enables the draftsman to quickly and accurately position the triangle where desired.

I claim:

1. In a drafting instrument, an upper guide member and a lower guide member, a triangle pivoted thereto intermediate said guide members 6 for relative motion between the same, one of said guide members having a, recess opening through one end thereof and a latch confined within said recess and having a nger piece extending therefrom beyond the free end of said guide member to overlie the lower guide member for operating said latch.

2. In a drafting instrument, an upper guide member and a lower guide member, a triangle pivoted to said guide members and lying between the same for movement between the guide members, a row of recesses on said triangle and a: latch on one of said guide members engaging said recesses to lock the triangle in any one of a plurality of adjusted positions, one of said guide members extending beyond its opposed guide member to form a gripping portion, said opposed guide member carrying said latch, said latch havf ing a finger piece extending from the end thereof and 4overlying the gripping portion on the other guide member.

3. In a drafting instrument, an upper guide member and a lower guide member having straight side edges, a, triangle pivoted thereto intermediate said guide members for relative swinging movement therebetween, said triangle being provided with an arcuate row of openings so located as to pass between the guide members as the triangle is swung, one of said guide members having a recess therein opening through the end thereof and extending to a point beyond the row of openings and facing the opposed guide member, and a latch pivotally mounted on said recess and having one end extending beyond the y open end thereof so as to be grasped to release the latch, the opposite 'end of the latch carrying a stud for engagement with any of the openings to lock the triangle in desired position, said latch member overlying the opposed guide member and terminating kflush with the end thereof so that the latch may be released by squeezing the free ends of the opposed guide members.

' OSCAR F. GRAFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

